David E. Wheeler wrote: > On Mar 27, 2009, at 6:40 PM, Bruce Momjian wrote: > > > Thanks, text updated: > > > > While semi-joins merely replace existing IN joins, anti-joins > > are a new capability for NOT EXISTS clauses (Tom) This improves > > optimization possibilities. > > I'm not enough of a relational algebra geek to really understand what > that means. Will there be a link or something to some documentation or > even, *gasp*, a blog entry explaining what this means and why it's > important?
Uh, not really; the optimizer stuff is usually quite vague and Tom might end update removing it once he goes over the release note anyway (he has in the past). I documented it because it is a user-visible change, I think, becuase it might show up in EXPLAIN. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
